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MG MGB Technical - Tube axle shaft, hub, and seal replacement (help!)

I removed my brake drum to investigate what looked too much like a leaking rear axle seal and found lots of gear oil so seal is bad. I also found that the rear hub (disc wheel / tube axle) could rotate several degrees left or right under the axle nut before engaging the axle. I pulled the nut and hub free of the axle and it looks like the splines on the hub and axle are worn out allowing this play. I am wondering if I am better off finding parts or a complete used axle? Has anyone replaced axles, seals, hubs recently?

Cliff

Cliff Maddox

Darn, I just threw away most of the parts you need. I just replaced my complete rear axle with one I rebuilt, hence the extra parts.

Contact me off-list if you need some contacts to find another axle, or just parts. If your diff gears are good and the axle is straight, then I'd suggest simply finding a new pair of axles and hubs. But also be sure to check the spider gear side for wear before going through the process of repair.
Steve Simmons

The hub should be clamped between two tapers which should prevent it moving relative to the axle shaft when the nut is tightened to 150 ft.lb. The inner taper is what the oil seal runs on, so if this is grooved you will need to replace this as well as the seal. The outer taper is a split washer under the nut. There has to be *some* clearance i.e. play in the splines or you would have to press the hub on to and off the half shaft. In practice it is an easy sliding fit, same as centre-lock wheels to hubs.

Are you sure it isn't the usual thrust washer wear in the diff you are seeing?

Breaking the taper between hub and shaft is usually the most difficult job. With that off you may be able to pry the old seal out of the end cap as is, but make sure you don't damage the inner taper it runs on. Failing that you will have to remove the backplate (four bolts), then lightly replace the hub and tap on the back of it with a mallet to pull the half-shaft, bearing and end-cap part way out. The you can tap the end-cap off the bearing to replace the seal.

Grease the new seal and lip, even though it runs in gear oil.

If the rest of the axle is good, and the half-shaft and hub really are damaged (and it may only be one of them) I'd just replace the worn parts. A complete used axle will almost certainly be an unknown quantity and you may get you a whole load of other problems.

And I can't believe anyone would chuck away parts, haven't you heard of "If you haven't found a use for something yet you haven't kept it long enough"? :o) I've still got a complete used disc wheel axle from 17 years ago.
Paul Hunt 2

Paul,

What I found is that with the axle bolt still installed and split pin in place that the hub could rock back and forth on the splines several degrees quite freely. When I removed the axle nut the hub came right off with no effort. I noticed the taper surface at the backplate side and the "axle shaft collar" which is the split washer fitting under the axle nut did not seem to be locking the hub against the axle but I thought that these are there to provide lateral location of the hub along the axle and that the splines alone would fix the hub around the shaft from free rotation. Looking at the splined end under the hub the splines are worn quite sharp where the hub sat and have also blued from heat and so I am thinking that this is excessive wear and both axle shaft and wheel hub should be renewed. I believe that the rest of the axle assembly is in good shape (it was silent). As far as I can tell the right side axle is in good shape with no leaks and no free movement. Because of this I agree that I am better off repairing than swapping. I will wait to fit new/used axle and hub parts and see if the two taper items also need to be replaced (or is there another way to tell?) Thank you for your advice it was very helpful.

Steve,
You are not alone...I confess that I have thrown away a treasure trove of old MG parts in days past. Not anymore though!

Cliff
Cliff Maddox

Following (after scolding!) is a copy from a recent thread, and I've posted all this quite a few times. There's more if you look it up.
***********
People who throw away parts are not getting any karma points; people who drive old & rare cars should realize that if everybody let the "clean & neat Jones" rule, then they wouldn't have a TC or similar. Thus they should know better and can expect severe punishments as they are admitted through the gates of Hell. Parts are like children - you are required to care for them to the best of your ability, and to see that they get good homes! If it costs you to store them or ship them to others, so be it - it's part of the price.
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Martin Layton, West Midlands, United Kingdom

Thanks for the reply Paul.

I pulled the shaft, and changed the bearing (It did need pressing off, and driving on), checking that the spacer between the bearing and shaft was the right way round. Once pulled off, it is obvious which way the spacer goes, there is an marked radius on the shaft that the concave face of the washer covers up.

The only marks on the old and new bearing is RMS-10, the old one is 0.873 thick, the new one measures 0.875" exactly (7/8" sounds a likely size to me!)

Both taper washers have machined splits in them, 2 in the oil seal washer, and one in the nut washer, so that they can compact into the tapered bore and lock to the shaft.

I did think that the outer washer was bottoming on the splines, but careful examination of the hub shows that the splines are inside the hub slightly, so it cannot be.

Even with a slightly wrong taper the clamping force from the hub nut should distort the hub enough to lock it up tight, how else can I get 150 ftlb at the nut? Something must be going tight.

I suspect the PO was trying to sort out the clonk from the axle, as on my test drive, I remarked on the clonk, and he told me it had just had new wheel bearings. (And I thought "I know what that is- thrust washers!")


I'm starting to think that I'm chasing the wrong end of the shaft, and the hub is locked, but the diff end is lifting when I shake the wheel. Both sides seem the same, and I wouldn't call the axle noisy, it has only done 90,000 miles.

I have been inside the axle, to renew the thrust washers, and the crownwheel wasn't loose, neither did the sun wheels seem unduly loose, but I wasn't looking for a problem other than thrusts then.
The splines at both ends of the shaft seem fine, but I suppose it doesn't need much wear to produce play that I can detect.

Looks like I may be swapping the axle if it fails the MOT next month, but it would probably be a good idea to try and pull someone elses wheel off to see if I actually have a problem!
*****
The hub tapers can wear from running loose, and many are. That in turn wears the splines. However, it should still lock up when tightened, if not it is usually that the nut is bottoming on the thread end runout/shoulder. I have sometimes found it necessary to fit a washer between the nut and taper collar to cure this. I put a thin coat of Permatex #2 on the inner collar - not on the tapered bit - between the collar and bearing to prevent oil leaking under the collar. Then anti-seize on the tapers, splines, and threads and nut face, torque to 150. Correctly done, the tapers themselves would drive the car without splines.
Another source of "clonk" that I keep posting and nobody acknowledges is a loose nut on the gearbox output shaft - sounds just like the RAX noises, and is commonly but not always associated with speedo readings that develop a sort of "high limit" = won't go over 60mph when warm.
FRM
FR Millmore

Cliff - it sounds like you have incorrect parts somewhere. I remember the earlier thread copied above by FRM, I checked my spare axle at that time and found I had about another 1/4" of thread to go when things were tightened down. I think the originator of that thread overcame it by putting a thick washer between the nut and taper washer. However with yours it seems like the looseness may have severely worn the hub and half-shaft, so these would be best replaced, and then by measurement make sure you have some unused threads, perhaps adding washers under the nut as required to ensure the hub is tightly clamped. However there has to be a spacer between the bearing and the shoulder on the half-shaft. If this is missing there will be a greater splined length sticking through the hub, which could explain why the nut is tightening down but not clamping the hub. But with replacement half-shaft, hub and bearing (and oil-seal) likely needed in your case you will have opportunity to check that. The spacer I refer to is 'handed' - it has one flat face and one concave, and the concave face must be against the shoulder on the half-shaft, the flat face against the bearing. Get that the wrong way round and you have the opposite problem - perhaps too much half-shaft sticking into the diff and not enough through the hub.
Paul Hunt 2

Thanks to all....I will report back what I find. No doubt something is not quite right as Paul says.

Regards,

Cliff
Cliff Maddox

This thread was discussed between 28/05/2007 and 01/06/2007

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